Skateboards are wheeled platforms typically less than 12 inches wide and less than 33 inches long, however, so-called long-board types are usually longer than 33 inches. Sets of wheels and wheel mounting structures (called “trucks”) are placed on one surface of a rigid platform, called a deck, and oriented such that the deck will roll on the attached wheels in a direction essentially parallel to its side edges. Placed so that the wheels contact the ground, a user stands on the opposite surface of the deck and using a scooter-like one-footed propelling motion, or gravitational force on sloping ground, the user is transported along with skateboard in an intended path.
One can create an electrically propelled skateboard by replacing a truck and its wheels with a new truck having wheels that contain a motor within each. Powered by a battery, the wheel motors propel the skateboard by rotating the wheels. A standard truck, regardless of the distance between its wheels, has an axle that protrudes approximately 1.4 inches on each side of the truck cross-member base. This 1.4 inch axle is the one to which each wheel is mounted using a threaded nut. However, with an electric propulsion wheel, the internal motor width will exceed 1.4 inches in order to produce sufficient torque. Thus, in order to retrofit a skateboard for electric propulsion, the standard wheels and trucks are replaced by wheels and trucks specifically designed for electric propulsion. An alternative way would be to attach a motor to the truck and use a drive belt to link the motor and the wheels. As such, the wheels would need to be modified with a pulley or gear, and the truck would need to be modified for a mounted motor. In addition, a subsystem containing battery and control circuitry must also be mounted below the skateboard deck.